In order to fulfill the goals set forth by the Generation IV International Forum, the current NERI funded
research has focused on the design of a Gas-cooled Fast Reactor (GFR) operating in a Breed and Burn
(B&B) fuel cycle mode. B&B refers to a once-through fuel cycle where low enriched uranium (less than
5 w/o 235U in U) subcritical assemblies are loaded into the core in equilibrium, yet in-situ plutonium
breeding carries the fuel through a discharge burnup on the order of 150 MWD/kgHM. The B&B fuel
cycle meets the GenIV goals of sustainability, economics, and proliferation resistance by increasing fuel
burnup without the need for spent fuel reprocessing, recycle, or reuse of any kind.
The neutronic requirements for B&B are strict and require an ultra-hard neutron spectrum. Therefore, the
GFR is ideally suited for this fuel cycle. In the present work the B&B GFR concept evolved into two
practical reactor designs, both of which build on extensive previous gas-cooled reactor design experience.